[libcamera-devel] [PATCH v3 09/11] libcamera: camera: Assert pipelines complete all requests

[Kieran Bingham]

When the camera manager calls stop on a pipeline, it is expected that
the pipeline handler guarantees all requests are returned back to the
application before the camera has stopped.

Ensure that this guarantee is met by providing an accessor on the
pipeline handler to validate that all pending requests are removed.

Signed-off-by: Kieran Bingham <kieran.bingham at ideasonboard.com>

---
Note:

I wanted to make PipelineHandler::active() a const function, but then
I'm unable to call it through invokeMethod(). Does invokeMethod support
calling const functions? Or did I do something obviously wrong?
---
 include/libcamera/internal/pipeline_handler.h |  1 +
 src/libcamera/camera.cpp                      |  3 +++
 src/libcamera/pipeline_handler.cpp            | 17 +++++++++++++++++
 3 files changed, 21 insertions(+)

diff --git a/include/libcamera/internal/pipeline_handler.h b/include/libcamera/internal/pipeline_handler.h
index 9bdda8f3b799..1410a06ebabe 100644
--- a/include/libcamera/internal/pipeline_handler.h
+++ b/include/libcamera/internal/pipeline_handler.h
@@ -80,6 +80,7 @@ public:
 
 	virtual int start(Camera *camera, const ControlList *controls) = 0;
 	virtual void stop(Camera *camera) = 0;
+	bool active(const Camera *camera);
 
 	int queueRequest(Request *request);
 
diff --git a/src/libcamera/camera.cpp b/src/libcamera/camera.cpp
index 7f7956ba732f..99b01633ff5f 100644
--- a/src/libcamera/camera.cpp
+++ b/src/libcamera/camera.cpp
@@ -1086,6 +1086,9 @@ int Camera::stop()
 	d->pipe_->invokeMethod(&PipelineHandler::stop, ConnectionTypeBlocking,
 			       this);
 
+	ASSERT(!d->pipe_->invokeMethod(&PipelineHandler::active,
+				       ConnectionTypeBlocking, this));
+
 	d->setState(Private::CameraConfigured);
 
 	return 0;
diff --git a/src/libcamera/pipeline_handler.cpp b/src/libcamera/pipeline_handler.cpp
index e3d4975d9ffd..c1ea4374b445 100644
--- a/src/libcamera/pipeline_handler.cpp
+++ b/src/libcamera/pipeline_handler.cpp
@@ -357,6 +357,23 @@ const ControlList &PipelineHandler::properties(const Camera *camera) const
  * \context This function is called from the CameraManager thread.
  */
 
+/**
+ * \brief Determine if the camera has any requests pending
+ * \param[in] camera The camera to check
+ *
+ * This method determines if there are any requests queued to the pipeline
+ * awaiting processing.
+ *
+ * \context This function is called from the CameraManager thread.
+ *
+ * \return True if there are pending requests, or false otherwise
+ */
+bool PipelineHandler::active(const Camera *camera)
+{
+	const CameraData *data = cameraData(camera);
+	return !data->queuedRequests_.empty();
+}
+
 /**
  * \fn PipelineHandler::queueRequest()
  * \brief Queue a request
-- 
2.25.1